The present invention relates generally to the field of fire alarm systems, and more particularly, is directed to a super sensitive fuse assembly for alarm devices.
Fire alarm systems as presently designed most frequently are responsive to the presence of heat and may be designed with either a fixed temperature response or with a rate of rise temperature response. The present invention is directed to that type alarm having components responsive to the presence of a fixed elevated temperature, for example, 165.degree. F., 136.degree. F., or other standard temperature setting.
Traditionally, alarm response to a predetermined elevated temperature has been accomplished by fusing a low melting temperature alloy such as eutectic solder to function either an electrical alarm circuit or a mechanical alarm circuit for alarm sounding purposes. One such device is disclosed in my co-pending application Ser. No. 478,928, filed June 13, 1974 now U.S. Pat. No. 3,938,115, entitled "Combination Smoke and Heat Detector Alarm" wherein a fusible eutectic compound has been shown positioned as an obstruction within a gas conduit between the compressed gas tank and the alarm sounding horn. Upon melting of the eutectic compound by elevated temperature in the vicinity of the device, the gas conduit obstruction is cleared and the alarm sounding apparatus is actuated.
It is the common practice to rate alarm devices by applying certain standard tests such as those designed and conducted by Underwriters' Laboratories, Inc. In this manner, designers, architects, engineers and fire protection specialists can design workable fire alarm installations with a reasonable degree of accuracy. By applying such standard tests, alarm sounding devices have been rated and standards of installation have been established to enable architects, fire safety engineers, safety specialists and others to design and install alarm systems within buildings in an orderly manner and in accordance with predetermined standards.
Alarm equipment of the type set forth has usually been rated by Underwriters' Laboratories, Inc. and others for a 25 foot space rating between detectors. That is, one such heat detection unit must be installed for every 625 square feet of floor area or as otherwise stated, the heat detection units should be installed with no more than 25 foot spacing between adjacent units. Previous detector designers in the field have been generally unsuccessful in developing heat detection systems responsive to a fixed an elevated temperature that were sensitive enough to be approved for installation at spacings greater than 30 feet.